Your First Aquarium: The Complete Beginner's Guide

Setting up an aquarium seems simple, but the choices you make now will determine how your tank develops later – and which fish you can ultimately keep. In this guide, we'll walk you through all the basic choices: tank size, substrate, filter systems, lighting, CO2, decor, and fish.

1. The size of your aquarium

The two questions you need to ask yourself are: how much space do I have, and what fish do I want to keep? For beginners, a ready-made starter tank (up to about 110 liters) is often the easiest route: affordable, easy to place anywhere, and complete with light, filter, and accessories.

The downside: the built-in equipment makes you dependent on one brand, and with larger fish, you'll reach the limits of the tank within a few years.

A large tank always requires sturdy furniture - a lot of weight goes into the water. The advantage: such furniture immediately offers storage space for equipment and care supplies.

2. Substrate and nutrient soil

Your choice depends on the type of fish. For cichlids and predatory fish, nutrient soil is usually not necessary - those tanks are often not (densely) planted. For a heavily planted community tank, nutrient soil saves you the hassle of separate liquid fertilization or root feeding, and often lasts more than 2 years.

Always choose fish and aquarium-friendly gravel, preferably smooth, so that bottom-dwelling fish like Kuhli loaches or Corydoras don't injure themselves. Always rinse gravel first - there's often still stone dust on it.

Step-by-step plan for building the substrate:

1. Apply a layer of nutrient soil 1-2 cm thick
2. Cover this with 3-5 cm of gravel or sand
3. Fill the tank halfway with water
4. Use your finger or tweezers to make holes in the substrate to plant plants

Want to know more about choosing the right substrate? Read our comprehensive guide: Choosing Substrate: Gravel, Sand, or Nutrient Soil?

3. Filter systems

The filter keeps your water free of harmful substances - the difference between life and death for many inhabitants. There are two main types.

Internal filter

Attached inside the tank itself, often with suction cups, or built into a compartment in starter tanks. Works with replaceable sponges or cartridges, possibly supplemented with carbon or ceramic biofilter material. Maintenance always takes place inside the tank.

External filter

Located outside the tank. A pump moves the water via a hose to the filter, where it flows through multiple layers of filter material, and then pumps it back. More space for different filter materials means more precise control of water parameters. External filters are mainly used for tanks above 100 liters; they are less suitable for small tanks and nano-aquariums.

4. Lighting

Lighting simulates daylight for your plants and fish. More important than intensity is often duration: count on 6 to 10 hours per day, depending on inhabitants and planting.

• Too little light: plants grow poorly, produce less oxygen
• Too much light: algae growth increases

If you have an algae problem, you can shorten the lighting duration or interrupt the light cycle (e.g., 4 hours on, 4 hours off, 4 hours on). A timer - sometimes built into the lighting, sometimes purchased separately - makes this much easier to manage.

5. CO2 systems

CO2 is not necessary for every aquarium, but it is an important nutrient for plants (and for moss and algae) in heavily planted tanks. There are three ways to add CO2:

• Tablets: convenient and effective as a boost, with limited influence on water parameters
• Liquid CO2: sufficient for most hobbyists, often combined with fertilization
• CO2 system (bottle + pressure regulator + bubble counter): the most accurate method, suitable for dosing down to the bubble, but also the most cumbersome - mainly used for larger tanks

Want to know more about fertilizing in combination with CO2? Check out our guide: Fertilizing Aquarium Plants: A Beginner's Guide

6. Wood, stones, and plants

Wood

Only use wood that has been specially treated for aquarium use. First, soak it in a bucket of water to remove dust and dirt, and keep it submerged until it is saturated and no longer floats (weigh it down with a stone if necessary). Note: wood can lightly yellow the water and turn filter material such as sponges brown - this is normal.

Stones

From broken stone to dragon rock: always buy stones from an aquarium specialist store to ensure they are safe for use in the tank. Underwater, stone always appears a shade darker than above. Rinse stones before use, and secure multiple stones together with aquarium glue to prevent collapse - even during maintenance.

Plants

Aquarium plants are suitable for almost any community tank, but are more difficult to combine with cichlids and predatory fish. Green plants are generally less dependent on extra fertilization due to photosynthesis; red plants usually require more nutrients.

Plants with above-ground roots - such as Anubias, Bucephalandra, and Microsorum - should not be planted in the substrate, but attached to wood or stone with aquarium glue or thread.

7. Fish

The choice of fish actually influences all previous choices, but the fish themselves are usually the last thing you add - first let the tank cycle for several weeks so that a stable bacterial culture develops.

Community tank

Houses multiple, non-predatory (often schooling) fish, such as the neon, guppy, swordtail, and Corydoras families, and algae eaters like Ancistrus.

Cichlid tank

Often larger in size with fewer inhabitants, because cichlids continue to grow. Not all species can be combined with each other - Malawi cichlids, for example, are quite dominant, and some species attack each other. Always get good information about this before putting species together.

Still in doubt?

Feel free to visit our store in Heinkenszand - we'd be happy to help you think about the right tank, equipment, and fish for your situation.